One evening a Thai student who is soon going to spend his first winter in Japan is talking with a Japanese friend

Foreign Student: The days are really getting shorter, aren't they?
Japanese:            Yes. By about five-thirty, it's competely dark.
F:                        In summer, I was able to play tennis until almost seven, but recently I have trouble
                           seeing the ball after four.
J:                        Dawn comes later, too, doesn't it?
F:                       Oh really? I usually sleep late, so when I wake up, it's already light.
J:                       What time do yo get up every morning?
F:                       Usually around 7:30.
J:                        Oh. I don't get up very early, either. As it gets colder, it gets more and more difficult
                          to get up in the morning.
F:                       When I think of the cold weather drawing near, I begin to dislike being in Japan.

             One December starts, it gradually colder in Japan. And the sun sets earlier each day. December 22nd                        
             or 23rd is the shortest day of the year